It's that sound effect that's triggered whenever Snake is discovered in "Metal Gear Solid". Many other games have comes along since its introduction 15 years ago, and much has changed to the formula. But sneaking around and getting caught, plus the associated sound effect has been a staple ever since.

Kotaku reports that Metal Gear's big boss, Hideo Kojima, thought about getting rid of the trope, in hopes of making "Metal Gear Solid V: The Phantom Pain" more realistic:

"I actually considered not including the '!' mark that appears when enemies discover you.

Considering the console specs, it would have been possible to substitute with facial expressions and gestures. But when the character visuals are that realistic, you need to have a certain element of 'ambiguity.'"

But those around him pointed out something else as well:

"The staff said, 'if you get rid of it, it'll cause an uproar!'"

Given how much the sound has been tinkered with already, i.e. David Hayter getting the axe, Kojima has some smart people around him.